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Tesla Coil Help!! Got only 3 days left to complete my project, plsss help

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LAN_403

ElectricalEngg.

Mon Mar 09 2009, 02:34PM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

Hi friends remember I posted a transformer help topic once
I have been collecting the material for my Tesla coil the last month
had to travel 7 hour to get my transformer

Now currently I have a configuration of

A Neon Sign Transformer - 6kV, 30 mA, mid point grounded
A Bottle Capacitor - 1.05 Micro Farads
A secondary winding with 1050 turns of 28 gauge wire (completed
Primary winding - not wound yet, the wire is 14 guage

Problem No. 1

Now my problem is that I built a capacitor with a beer bottle of my dad, took one terminal from the water + salt solution and other from the aluminum foil wrapped around it.
When I checked the capacitance, it was pretty high 1.05,

so I thought Ill increase the inductance but now I don't know what voltage rating my capacitor has.

I require one which has a voltage rating of at least 12kV as per theories and dont even know if my capacitor can hold that or not

Can you guys guide me on how to test it?

I tried charging it for like 5 seconds then short circuit the terminals but I didn't see any spark :(

Problem No. 2
The only diagram of the circuit for mid point grounded transformer I found is this one
and I dont understand how can he put live and neutral in same input terminal
2s0imbd

and my tranformer is like this
23msw2a

Now I am confused where the hell was live terminal connected in the circuit diagram or if you guys have a proper circuit diagram, then pls post it for me :)

I have a mid point grounded neon transformer.

Those are the only two problems I am facing right now, please help me guys, its my college project and I will be doomed if I dodnt make it :(

Thanks :)

Tigeris

Mon Mar 09 2009, 05:11PM

Registered Member #1656 Joined: Wed Aug 27 2008, 03:28PM
Location: Pittsburgh PA
Posts: 53

The glass bottle thing i cant help you with much...im using the same thing and not getting good results with them. As far as the Xformer, do you have any pictures of it you can upload? The outputs on the transformer are both hot ( + ) there is no real "neutral". Try googling "tesla coil plans"

LithiumLord

Mon Mar 09 2009, 06:37PM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

so, first of all - 1.05uF?! Either there is something wrong with your measurements or that beer bottle is more of a beer storage facility ;)
The xformer usage schematic is not really any good at all btw - not only there's no RF filtering to protect the NST against any primary currents, but also the capacitive secondary feedback current is cut off-ground with NST acting as a choke. Any primary strike means a certain death of your NST in this case, without those strikes it will not live any long either however.
For your xformer, just ground the neutral output to a good RF ground, bypass it to one or both primary inputs with a cap, set up a protective gap across the NST output and, preferably with an RF-filter, rig it to the coil circuit.

Ultra7

Mon Mar 09 2009, 06:38PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Problem 1.
You didn't make just one beer bottle cap did you?
Read this.

Pay close attention to the part where he describes the salt water capacitor.

Problem 2.
The Neon Transformer you have should have two small insulated terminals labeled L and N.
Those are for Line and Neutral.
Then it should have two larger insulated terminals without any labeling = These would be your HV out.
Finally there should be a threaded bolt attached to the outer case = this would be ground.
Remember: Not all NST's are created equal though, so we should have a picture of yours to find out what you have. For instance, if you have a Switch mode NST, then you may not ever get your coil to work.

Problem 3.
You probably should do some more reading, as building a Tesla Coil can be very dangerous.
Here are some good sites.
Safety

Deepfried Neon

Tesla map

ElectricalEngg.

Tue Mar 10 2009, 11:01AM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

Now I am scared

Just when I thought I have everything under control

@Tigeris:I will get the pics of the transformer as soon as possible but I guess probably on day after tomorrow coz its in my college where I work on it and it will be closed tomorrow due to local festival.

LithiumLord:I have been reading on internet that the capacitance should be very low but well this is what I got :(
1.05 checked with various instruments even with a LCR meter.
and for the RF filter thing can we just use an MCB or fuse?
rest I am a bit confused right now with what to do and I have to finish it within 10 days from now :(

Ultra7: I am not sure now :( but well I can get the bottle capacitors not that tough, I can make them at home :)

and for transformer, well all the terminals have threaded bolts :(
There are total 4 terminals , 2 on input and 2 on output
Ill post the pics you mark what is what for me thx
and Ill also confirm the supplier if possible on phone, cant visit him, he lives 7 hours away from me :(

and yeah I already read all those sites :)
I have collected too much data on the internet and well now just have to put it into practical use :)

I operate stuff only under my teachers supervision just to be safe :)

Edit: Ok I thought I cant wait for that long coz my teachers will get angry if I will not work on day after tomorrow on my project.
so here I found an exact transformer shape as mine and well showed how terminals of mine are :)

2q2l4xt

Now ok just to make it easy for me
can someone roughly make the diagram using this transformer and tell me how to connect this in circuit. :)

so help me , I am really too scared now, if I don't make it now then I am like dead as just about 15 days ago when I explained the project properly to my teachers, they not only said me to build it in fact I am not gonna represent my college in tech-fest(just like a science fair) in like first week of april.

so basically if I am unsuccessful, then I am doomed:-((

LithiumLord

Tue Mar 10 2009, 11:32AM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

Of course it may be 1.05, but surely not uF ;)
As for the xformer, the "IDK" (XD) input to the left goes to your RF ground, the one to the right goes to the neutral mains terminal, bypass them with a 0.1-1uF cap mains-rated or bigger (500v feels right) so any stray inductance will not cause any spikes across the windings. Now just rig a protective gap (no midpoint) across the secondary (left "IDK" to live output) - and rig the rest of the coil circuitry across the output. As for the filter, the most simple one is just a choke to be added into the coil's live wire, in this case also a small cap across the NST output is highly recommended.

Steve Conner

Tue Mar 10 2009, 12:31PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

If the transformer only has one HV output terminal, then it isn't "mid point grounded". A mid point grounded transformer would have two HV terminals with large insulators.

If we assume that it only has one HV terminal, and the other end of the HV winding is connected to the case, then the way to hook it up is like LithiumLord said. The two terminals on the left are the HV output, and the two on the right are the mains input.

The schematics posted here are terrible, the transformer should connect across the spark gap, like so:

And when wired like this, a small coil may be OK without a safety gap.

1.05nF is about right for a beer bottle cap. 1nF = 0.001uF

ElectricalEngg.

Sun Mar 15 2009, 01:13PM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

sorry for late reply firends :( was having probs with internet lately

and yeah sorry again I just want to confirm the final reading for the capacitor
Its 1.05 pF
not uF sorry for that confusion :(

and yeah I cleared the confusion of transformer terminals

here are the final terminal configuration

2w5nioi

and the circuit diagram I made acc to these terminals, friends pls confirm this circuit diagram for me :)

A72xl

@LithiumLord would a safety gap be better than a choke?
and the small cap across output you said, whats that for? pf improv?

and yes The Capacitor

Friends I wanna ask if a capacitor made with MMC capacitors of TV will better?
They are pretty cheap but I have one problem, those have high capacitance value, but I read abt tesla coil that the capacitor should have low capacitance value:-((

and yes I was making a spark gap like this

1toktt

the real one will have screws infront of eachother and not at any angle like in the pic lol

is it ok?
the screws are of copper and are adjustable. :)
I know might not be as efficient, but easy to make:-p

My current configuration of Tesla Coil Is:

Transformer: Neon Sign Transformer, 220/6kV, 30 mA, mid point grounded to case.

Secondary Winding: 28 Guage Wire wound on a 2 inch dia PVC pipe. 1050 turns.

Primary Winding: Not wound yet but to be wound on 4 inch dia PVC pipe with a 14 Guage Copper Wire.

Capacitor: Still to decide between the bottle capacitors or MMC capacitors. Made one bottle capacitor and got a capacitance reading of 1.05 pF

Spark Gap: Static Spark Gap(adjustable screws type)

help me guys I only got this week left :(

I am happy that I finished secondary ^_^

Thanks again for your help friends, you all are great:-)

Good Day
Kashish Malhotra

TheBoozer

Sun Mar 15 2009, 04:10PM

Registered Member #1535 Joined: Wed Jun 11 2008, 11:37PM
Location: Northeastern Pennsylvania - USA
Posts: 117

1.05pF ????

1000 times that would be 1.05nF, and that's still so little bang energy. :(

ElectricalEngg.

Sun Mar 15 2009, 05:40PM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

TheBoozer wrote ...

1.05pF ????

1000 times that would be 1.05nF, and that's still so little bang energy. :(

Yeah I know

thats why I thought I was looking for MMC capacitor bank

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